Wireless systems for packet data transfer typically comprise a link layer protocol that supports reliable acknowledged data transfer modes. With such arrangements, transmission errors can be corrected by Automatic Repeat Request (ARQ) protocols. Such ARQ protocols utilize packet data units that can have either a fixed size or variable size that is chosen to match the radio resource capacity.
For 2.5/3G systems which have a fixed physical layer timing structure (i.e., data blocks are transmitted with distinct durations which can include a variable amount of data due to factors such as modulation schemes utilized, link adaption, etc.), data rates are typically too small to permit data packets (from the open systems interconnection network layer (L3)) to fit within a single transmission frame (corresponding to a single open systems interconnection data link layer (L2) packet data unit). Therefore, with L3 data packets that do not fit exactly into the provided radio resources, segmentation is required to build two or more corresponding L2 packet data units. As a result, additional processing resources are consumed and complexity of the protocol is increased. Furthermore, as medium access control (MAC) scheduling of link layer packet data units is conducted independently of the network layer data packets, the boundaries of the data packets are not always properly considered, which results in additional user-perceived delays (especially when a small part of a data packet is transmitted in a subsequent frame).
Accordingly, it will be appreciated that there remains a need for an improved technique for processing data packets for transmission via a physical layer.